Screen apparatus for television receivers



Oct 5, 1937. I K. SCHLESINGER 2,094,677

SCREEN APPARATUS FOR TELEVI S ION RECEIVERS Filed March 23, 1936 Patented Oct. 5, 1937 SCREEN APPARATUS FOR TELEVISION RECEIVERS Kurt Schlesinger, Berlin, Germany Application March 23, 1936, :Serial No. 70,425 In Germany March 29, 1935 3 Claims. (01. 250-36) tribe The invention relates to scanning appa- According to the invention, a remedy is proratus supplying deflection voltages to the defiecvided by the fact that at some point between the tion systems of television tubes. relaxation-oscillation generator I, 2, 3 and the It has been found that with scanning appa consuming apparatus 8, 9 there is provided a cirratus for television receivers producing linear cuit element, which transmits the high frequen- 5 movement of the image point which make use of cies of the relaxation curve in preference to the amplifying tubes for amplifying the saw-tooth basic frequency thereof. In other words, there Voltages, interfering distortions result in the imis connected between relaxation oscillation genage owing to the curved characteristic of the erator and consuming apparatus, and preferably,

10 amplifying tubes. therefore, in front of the grid circuit of thesub- 10 In the drawing Fig. 1 shows a circuit diagram sequent amplifier 5, a coupling member which of a scanning apparatus constructed according to already discloses a declining degree of transmisthe invention. sion in the case of the basic frequency of the Fig. 2 shows a saw-tooth voltage curve plotted relation oscillation-a so-called high-pass. With respect to the time. In Fig. l the high-pass according to the in- 15 In Fig. 1 there is shown a typical relaxationvention is designated in, H. The basic frequency oscillation connection system, in which a 0011- of the relaxation oscillation is no longer able to denser 2 is charged through the medium of a traverse the condenser Ill. It accordingly sufvery large resistance 3 by an anode battery i. fers at the resistance H a loss of potential which An amplifying tube 5 is coupled by way of a is designated by the potential divider I l-i2. 20 condenser E with the condenser circuit I, 2, 3, The higher frequencies of the saw-tooth curve and the amplified potential is taken from its traverse the condenser Ill and accordingly arrive anode resistance '5 and conducted to the defiectat the grid of 5 without dissipation, i. e., in prefing plate 8 of the Braun tube 9. erence. In certain cases the resistance ll may It is known that by wasting potential, i. e., by also be omitted. In the following there are quoted 5 adjusting the circuit so that very small oscillaby way of example indications in respect of the tion amplitudes at the condenser 2, and using a numerical dimension. d. c. potential source 4 which is fifty to one hundred times greater than the maximum po- Image change apparatus:

tential reached by the condenser the potential it; fi gggg''g "fibg g jgggg 30 curve reaching thegrid of the amplifying valve g 1 p 01 mf 5 may be rendered strictly linear. The deflecting Resistance 1 6; ohms potentials applied to the Braun tube 8, however, 2 Line jd '"z g g f"' are nevertheless not linear with respect to time. Number lines pp 180 er image 35 Fig. 2 shows the nature of the curve of this latter B 10 ire uenc flag 8 eriods 35 oscillation. The curve of the voltage applied to o 1 1 6 ds the grid of valve 5 is represented by Ill and has a g up 0 X 2 g f strictly linear ascent. The voltage capable of bez g ig ig 6 6 ing utilized at the Braun tube 9 is always as rep- Resistance 5: me Ohm .0 resented by the curve ll. This distortion is not g 4.0 to be explained by incorrect adjustment of the The basic frequency in the case of this high grid bias of 5, but still remains even if the valve 5 pass is weakened in a ratio of has been carefully adjusted to operate on the linear range of its characteristic.

45 It is accordingly assumed that the explanation 10 45 for the error is to be found in a curvature in the i. e., by 10%, and the high frequency is transcharacteristic occurring in general in the case of mitted without loss. It is possible with highelectronic tubes. The error itself is merely of pass couplings of this kind, which according to the order of a small percentage, i. e., is very small. the invention may also be introduced into later According to Langmuirs law of emission, the circuits, for example before the Braun tube, to 50 steepness of a characteristic must increase with perform a compensation of the natural curvature the anode current. As a matter of fact there is of the characteristic of the tube. an error of this kind in the case of all relaxation The same effect as obtained by the condenser apparatus which have been tested by the applil0 and the resistance ll may also be obtained cant. in certain cases, viz., in the case of low-ohmic 55 grid resistances l2, by a series choke I3. member l8, H is then omitted.

I claim:

1. A scanning apparatus for television receivers comprising a relaxation oscillation generator, said generator producing voltages of saw-tooth wave form having higher frequency and lower frequency components, an amplifier and. coupling means comprising means for passing said higher frequency components better than said lower frequency components for coupling said amplifier with said relaxation oscillation generator.

2. A scanning apparatus for television receivers ccmprising'a relaxation oscillation generator, said generator producing voltages of saw-tooth wave form having higher frequency and lower fre- The quency components, an amplifier and coupling 7 means comprising means for passing said higher frequency components better than said lower frequency components for coupling said amplifier with said relaxation oscillation generator, said means consisting of a condenser and a resistance connected in parallel.

3. A scanning apparatus for television receivers comprising a relaxation oscillation generator, said generator producing voltages of saw-tooth wave form having higher frequency and lower frequency components, an amplifier and coupling means comprising means for passing said higher frequency components better than said lower frequency components for coupling said amplifier with said relaxation oscillation generator, said means consistingof a resistance and a choke connected in series.

KURT SCHLESINGER. 

